Sergio Parisse has apologised to his teammates and fans after getting sent off while playing for Stade Francais yesterday.
The Italy captain was shown a red card for allegedly insulting the referee, and faces a minimum of a six-week ban if found guilty of the offence.
The 29-year-old wrote on Twitter: "Sorry to my teammates and fans for the red card, which I find too harsh! I never insulted [referee Laurent Cardona]."
Parisse would miss the rest of the Six Nations if found guilty at a hearing due to take place in the coming days.
Italy face Wales next Saturday, having started the tournament with a win over France before losing to Scotland last week.